Long-term metabolic control after pancreatic transplantation with enteric exocrine diversion was evaluated in 42 Type I (insulin-dependent) diabetic pancreas recipients with functioning grafts for 1 to 7 years. Glycaemic control (fasting blood glucose, glycosylated haemoglobin A1c, oral and intravenous glucose tolerance tests) was normal or near-normal in most patients, and showed no deterioration with time. In ten patients with functioning grafts for 5 years there was a small, but significant, improvement in the glucose control at 3 to 5 years as compared with that at 6 months post-operatively. In the latter recipients the number of acute rejection episodes correlated negatively with the intravenous glucose tolerance at 6 months (r = -0.64, p less than 0.01) and at 5 years (r = -0.60, p less than 0.01) after transplantation, respectively. The glycaemic control at 6 and 12 months after transplantation was similar whether segmental (n = 35) or whole-organ (n = 7) pancreatic grafts had been used. In six non-uraemic recipients who had received a pancreas transplant alone the serum cholesterol increased in all but one patient (0.05 less than p less than 0.1), and the LDL/HDL-cholesterol ratio was significantly higher (p less than 0.005) one year after transplantation than before. Conversely, in six diabetic patients who had lost the function of their single pancreatic grafts the lipid and lipoprotein profiles remained unaltered. It is concluded that the long-term glycaemic control after segmental or whole-organ pancreatic transplantation with enteric exocrine diversion remains essentially normal in most recipients, and it may even improve with time.(ABSTRACT TRUNCATED AT 250 WORDS)